2.330 QUERY_REWRITE_INTEGRITY

QUERY_REWRITE_INTEGRITY determines the degree to which Oracle must enforce query rewriting. At the safest level, Oracle does not use query rewrite transformations that rely on unenforced relationships.
Property Description

Parameter type

String

Syntax

QUERY_REWRITE_INTEGRITY = { enforced | trusted | stale_tolerated }

Default value

enforced

Modifiable

ALTER SESSION, ALTER SYSTEM

Modifiable in a PDB

Yes

Basic

No

Oracle RAC

Multiple instances can have different values.

QUERY_REWRITE_INTEGRITY is relevant for materialized views as well as for foreign key constraints in NOVALIDATE state.

Values

  • enforced

    Oracle enforces and guarantees consistency and integrity.

  • trusted

    Oracle allows rewrites using relationships that have been declared, but that are not enforced by Oracle.

  • stale_tolerated

    Oracle allows rewrites using unenforced relationships. Materialized views are eligible for rewrite even if they are known to be inconsistent with the underlying detail data. You must set the QUERY_REWRITE_INTEGRITY initialization parameter to stale_tolerated before querying an external table in the In-Memory Column Store (IM column store).

If a foreign key constraint is in NOVALIDATE state, join elimination is not done when QUERY_REWRITE_INTEGRITY=enforced. This means that queries with joins over a foreign key constraint that is in RELY NOVALIDATE state can potentially take longer to parse and execute as the optimizer does not trust the RELY.

See Also: